I like to use a humidity box to help with bad sheds. You'll need a tupperware container or a plastic bin that is just large enough to hold your snake. Make sure it has a lid. You will also need a heating pad on a thermostat, your temperature gun, and two wash cloths or hand towels.
Warm the heating pad up to 85-88F (no higher). Put one clean washcloth or hand towel on the bottom of the container so that your snake will have something to grip.
Put an inch or two of warm water (no warmer than 85F - check this with your temp gun) in the container.
Put the snake in the container and make sure it isn't completely submerged - you don't want an accidental drowning.
Soak the second washcloth/hand towel in warm water, then put it loosely on top of the snake - make a little snake sandwich.
Put the lid on the container and leave the snake in there for 30 minutes to an hour.
Monitor your snake while it's in the humidity box to be sure all is well.
Just moving around between the cloths will help remove a lot of shed; when you remove the snake you can also use one of the damp cloths to gently remove remaining shed.
If there's still quite a bit of stuck shed, repeat the process over the next day or two.
There are products out there like "Shed-ease" that you spray or rub on the snake to supposedly assist with shedding. I've never used those as I am very cautious about any chemicals around my animals, especially since warm water/high humidity works fine.